Sample bulk/batch usage:
@echo off
setlocal
SET IN_DIR=%USERPROFILE%\My Documents\My Kindle Content
SET DEST_DIR=%IN_DIR%_drmfree
SET KEY_FILE=mykeyfile.k4i
mkdir "%DEST_DIR%
k4mobidedrm.py -k %KEY_FILE% "%IN_DIR%" "%DEST_DIR%
echo done, see %DEST_DIR%
cd /d "%DEST_DIR%"
start .
endlocal